//检查邮箱用户名
function _checkusername( name, checklength ) {
	var i = 0;
	var j = 0;
	var ch;
	var TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_-.0123456789";
	var NUM = "0123456789";

	if( checklength && (name.length<1) ) {
		alert( "User name format error!" );
		return false;
	}

	if( !checklength && (name.length==0) )
		return true;

	for( ; i<name.length; i++ ) {
		ch = name.charAt( i );
		if( TABLE.indexOf(ch) == -1 ) {
			alert( "User name format error!" );
			return false;
		}
	}
	
	ch = name.charAt(i++);
	j = TABLE.indexOf(ch);
	if (j == -1 || j > 52) {
		alert( "User name format error!" );	
		return false;
	}

	return true;
}

//检查邮箱用户密码
function _checkpassword( passwd ) {

	var i = 0;

	var ch;

	var TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_-.0123456789";



	if( passwd.length <6 ) {

		alert( "Password length must more than 6!" );

		return false;

	}



	for( ; i<passwd.length; i++ ) {

		ch = passwd.charAt( i );

		if( TABLE.indexOf(ch) == -1 ) {

			alert( "Password format error!" );

			return false;

		}

	}



	return true;

}